TB 26-04 美国国家航天局（NASA）化学平衡与应用（CEA）代码的更新与现代化

如需更多信息，请联系格伦研究中心（Glenn Research Center）的Mark K. Leader，邮箱：[email protected]

For more information, contact Mark K. Leader, Glenn Research Center, [email protected]

美国国家航天局（NASA）的化学平衡与应用（Chemical Equilibrium with Applications, CEA）代码是推进系统分析的基础工具。它提供在NASA及更广泛的航空航天领域中使用的化学平衡、火箭性能、激波和爆轰计算。NASA工程与安全中心（NASA Engineering and Safety Center, NESC）的TI-22-01730项目将传统的CEA2 Fortran代码现代化为CEA v3，这是一个Fortran 2008面向对象的软件包，具有扩展的接口支持、更新的热化学数据、改进的可维护性以及大幅提升的工作流集成度。现代化后的代码在保留与传统CEA输入工作流向后兼容性的同时，实现了从Python、C、MATLAB和自动化设计研究等现代分析环境中的直接调用。

NASA’s Chemical Equilibrium with Applications (CEA) code is a foundational tool for propulsion system analysis. It provides equilibrium chemistry, rocket performance, shock, and detonation calculations used across NASA and the broader aerospace community. NASA Engineering and Safety Center (NESC) Activity TI-22-01730 modernized the legacy CEA2 Fortran code into CEA v3, a Fortran 2008, object-oriented software package with expanded interface support, updated thermochemical data, improved maintainability, and substantially improved workflow integration. The modernized code preserves backward compatibility with legacy CEA input workflows while enabling direct use from modern analysis environments, including Python, C, MATLAB, and automated design studies.

背景

Background

CEA2于2002年发布，长期以来广泛用于推进和热化学分析。然而，由于缺乏子程序接口，最初的过程式Fortran实现变得越来越难以维护、扩展和集成到现代工程工作流中。当前的推进分析日益需要自动化参数扫描、与其他建模工具及工程工作流的集成，以及对新兴推进剂和燃料（包括绿色推进剂和可持续航空燃料）的支持。这些需求推动了一项全面的现代化工作，旨在保留CEA经过验证的技术基础，同时提高其可维护性、可用性以及与现代工程软件的集成度。

CEA2 was released in 2002 and has remained widely used for propulsion and thermochemistry analysis. However, the original procedural Fortran implementation became increasingly difficult to maintain, extend, and integrate into modern engineering workflows due to the lack of a subroutine interface. Current propulsion analysis increasingly requires automated parametric sweeps, integration with other modeling tools and engineering workflows, and support for emerging propellants and fuels, including green propellants and sustainable aviation fuels. These needs motivated a comprehensive modernization effort to preserve CEA’s validated technical basis while improving its maintainability, usability, and integration with modern engineering software.

技术改进

Technical Improvements

现代软件架构

Modern Software Architecture

CEA v3采用Fortran 2008实现，使用了面向对象的数据结构、更严格的类型定义以及线程安全的平衡求解器架构。该软件支持Fortran、C、Python、MATLAB和Excel接口。这些接口使CEA能够直接用于自动化分析流水线、多学科设计框架以及大规模实验设计研究。通过传统的命令行接口支持向后兼容性，允许现有的CEA输入文件和工作流以最小的干扰进行迁移。

CEA v3 is implemented in Fortran 2008 using object-oriented data structures, stricter typing, and a thread-safe equilibrium solver architecture. The software supports Fortran, C, Python, MATLAB, and Excel interfaces. These interfaces allow CEA to be used directly in automated analysis pipelines, multidisciplinary design frameworks, and high-volume designof- experiments studies. Backward compatibility is supported through a legacy command-line interface, allowing existing CEA input files and workflows to be carried forward with minimal disruption.

扩展的物种和热力学数据

Expanded Species and Thermodynamic Data

热力学数据库已得到扩展，以支持与当前NASA应用相关的额外推进剂和燃料，包括ADN、HAN和LMP-103S等绿色推进剂成分，以及正丁醇（n-Butanol）等可持续航空燃料候选物。这种扩展的物种覆盖范围提高了CEA在下一代推进、绿色推进剂和可持续航空燃料研究中的适用性。

The thermodynamic database has been expanded to support additional propellants and fuels relevant to current NASA applications, including green propellant constituents such as ADN, HAN, and LMP-103S, and sustainable aviation fuel candidates such as n-Butanol. This expanded species coverage improves the applicability of CEA for next-generation propulsion, green propellant, and sustainable aviation fuel studies.

新的建模能力

New Modeling Capabilities

CEA v3增加或改进了对多种建模能力的支持，

CEA v3 adds or improves support for several modeling capabilities,

包括：

including:

- 支持直接集成和大规模计算的子程序接口

- Subroutine interface enabling direct integration and high-volume calculations

- 负反应物量

- Negative reactant amounts

- 惰性碳氢燃料表示，包括RP-1、Jet-A和JP系列燃料

- Inert hydrocarbon fuel representations, including RP-1, Jet-A, and JP-series fuels

- 用于与优化和灵敏度分析工作流耦合的解析总导数

- Analytic total derivatives for coupling with optimization and sensitivity analysis workflows

性能改进

Performance Improvements

对于独立使用，CEA v3中的单个平衡计算比相当的CEA2计算稍慢，因为现代化架构和增加的鲁棒性引入了额外的计算开销。在代表性测试中，单次计算速度慢了约40%，但绝对差异每个案例仅约0.004秒。然而，现代化架构为多案例工作流提供了显著的性能优势，这在实验设计研究、参数扫描、优化和不确定性分析中非常常见。在一项基准测试中，使用CEA v3完成108,500个案例的扫描仅需约1.11秒，而使用CEA2则需要约15分钟。这相当于该工作流的运行时间缩短了约800倍。这些改进使得大规模推进权衡研究和自动化设计空间探索变得更加实用。

For standalone use, individual equilibrium calculations in CEA v3 are moderately slower than comparable CEA2 calculations because the modernized architecture and added robustness introduce additional computational overhead. In representative testing, a single calculation was approximately 40 percent slower, but the absolute difference was only about 0.004 seconds per case. However, the modernized architecture provides substantial performance advantages for multi-case workflows, which are common in design-of-experiments studies, parametric sweeps, optimization, and uncertainty analyses. In one benchmark, a sweep of 108,500 cases completed in approximately 1.11 seconds with CEA v3, compared with approximately 15 minutes using CEA2. This corresponds to an approximately 800-times reduction in runtime for that workflow. These improvements make large-scale propulsion trade studies and automated design-space exploration significantly more practical.

工程使用指南

Guidance for Engineering Use

NASA工程用户应考虑以下指南：

NASA engineering users should consider the following guidance:

- 尽可能使用CEA v3进行新的推进和热化学分析，以利用其现代化的接口、扩展的数据库和改进的工作流集成。

- Use CEA v3 for new propulsion and thermochemistry analyses when possible to take advantage of the modernized interfaces, expanded database, and improved workflow integration.

- 使用Python、MATLAB或C接口进行自动化工作流，包括参数扫描、优化研究和迭代设计分析。

- Use the Python, MATLAB, or C interfaces for automated workflows, including parametric sweeps, optimization studies, and iterative design analyses.

- 当相关物种已包含并针对预期应用进行验证时，使用更新后的物种数据库进行绿色推进剂和可持续航空燃料研究。

- Use the updated species database for green propellant and sustainable aviation fuel studies when the relevant species are included and validated for the intended application.

- 当需要与传统CEA工作流或输入文件保持连续性时，使用经典的命令行接口。

- Use the classic command-line interface when continuity with legacy CEA workflows or input files is required.

- 在将既有的CEA2工作流迁移到CEA v3时，保留适当的工程审查和验证，特别是对于任务关键型分析或依赖于传统假设的案例。

- Retain appropriate engineering review and validation when transitioning established CEA2 workflows to CEA v3, particularly for mission-critical analyses or cases that depend on legacy assumptions.

参考文献

References

- NASA/TM–20260007987

- NASA/TM–20260007987

- CEA文档：https://nasa.github.io/cea

- CEA documentation: https://nasa.github.io/cea

- CEA存储库：https://github.com/nasa/cea

- CEA repository: https://github.com/nasa/cea

如需更多信息，请联系格伦研究中心（Glenn Research Center）的Mark K. Leader，邮箱：[email protected]

For more information, contact Mark K. Leader, Glenn Research Center, [email protected]